Hydrogen generation apparatus and fuel cell system

1. A hydrogen generation apparatus comprising:

a reformer configured to generate a hydrogen-containing gas by using a raw material and steam;

a raw material passage through which the raw material that is supplied to the reformer flows, one end of the raw material passage being connected to the reformer;

a most downstream valve disposed on the raw material passage;

a hydrodesulfurizer provided downstream from the most downstream valve on the raw material passage, configured to remove a sulfur compound from the raw material, and the raw material passage passes through the hydrodesulfurizer;

a sealer provided on a passage downstream from the reformer and configured to block communication between the reformer and an outside of the hydrogen generation apparatus; and

a depressurizer provided on the raw material passage at a portion connecting the hydrodesulfurizer and the reformer and configured to release, to an atmosphere, pressure in the reformer that has increased after the sealer is closed,

wherein no valve is provided on the raw material passage between the hydrodesulfurizer and the reformer.

2. The hydrogen generation apparatus according to claim 1 , comprising:

an evaporator configured to generate steam; and

a water passage connected to the evaporator, wherein

the evaporator is provided on the raw material passage, and

in the evaporator, the depressurizer is disposed at a position away from a passage through which water having flowed into the evaporator flows.

3. The hydrogen generation apparatus according to claim 2 , wherein

in the evaporator, the depressurizer is provided on a passage upstream from a water inlet of the evaporator, the water inlet allowing water from the water passage to flow into the evaporator.

4. The hydrogen generation apparatus according to claim 3 , wherein

in the evaporator, the depressurizer is disposed at a position above the water inlet.

5. The hydrogen generation apparatus according to claim 1 , wherein

the depressurizer includes a branch passage and a depressurizing valve provided on the branch passage, and

the branch passage includes a portion leading to the depressurizing valve being, at least partially, formed as an upward slope.

6. The hydrogen generation apparatus according to claim 1 , wherein

the depressurizer includes a branch passage, a depressurizing valve provided on the branch passage, and a filter provided upstream from the depressurizing valve.

7. The hydrogen generation apparatus according to claim 1 , wherein:

the hydrodesulfurizer includes:

a hydrodesulfurization catalyst; and

a space formed below the hydrodesulfurization catalyst;

wherein the raw material flows through the raw material passage within the hydrodesulfurizer after the raw material has passed through the hydrodesulfurization catalyst, and

the raw material passage is open to the space and includes an upward slope portion.

8. A fuel cell system comprising:

the hydrogen generation apparatus according to claim 1 ; and

a fuel cell configured to generate electric power by using the hydrogen-containing gas that is supplied from the hydrogen generation apparatus.

9. The hydrogen generation apparatus according to claim 1 , further comprising a hydrogen gas passage configured to supply a hydrogen-containing gas to the hydrodesulfurizer.

10. The hydrogen generation apparatus according to claim 9 , wherein the hydrogen gas passage is connected to the hydrodesulfurizer so that hydrogen-containing gas generated by the hydrogen generation apparatus is supplied to the hydrodesulfurizer.

11. The hydrogen generation apparatus according to claim 1 , wherein the hydrodesulfurizer includes at least one of a copper-zinc catalyst, a zinc oxide catalyst and a Mo-based catalyst.